Certain microreplicated optical products, such as described in U.S. Pat. Nos. 5,175,030 and 5,183,597, are commonly referred to as a “brightness enhancing films”.
Brightness enhancing films are currently used in various (e.g. LCD) hand-held display devices, such as cell phones, PDAs, and MP3 players, to increase battery life and display brightness. An industry trend, particularly for hand-held display devices, is to produce increasingly thinner devices.
Brightness enhancing films have been prepared from high index of refraction polymerizable compositions. As described in Lu et al., U.S. Pat. No. 5,175,030, and Lu, U.S. Pat. No. 5,183,597, a microstructure-bearing article (e.g. brightness enhancing film) can be prepared by a method including the steps of (a) preparing a polymerizable composition; (b) depositing the polymerizable composition onto a master negative microstructured molding surface in an amount barely sufficient to fill the cavities of the master; (c) filling the cavities by moving a bead of the polymerizable composition between a preformed base (such as a PET film) and the master, at least one of which is flexible; and (d) curing the composition.